Since a previous experiment revealed that late stage pregnancy exposure of CF-1 mice to high frequency noise resulted in a significant increase in fetolethality, the hormonal/biochemical correlates of this effect were sought. Since corticosterone levels were measured in a previous experiment (see Z01 ES 50044-02 LEB) and found to be unaffected by noise exposure, this experiment focused on catecholamines, Exogenous introduction of these substances has been found to increase fetolethality. Exposure period was 12 hours (noon to midnight) and noise was a swept band at 18-20 KHz. Reproductive-teratogenic effects determined by standard techniques included lower maternal and fetal weights increased entire litter resorption, and a significant increase in the total number of malformed fetuses. A suggestive increase in plasma epinepherine levels was noted (p less than 0.06) and a significant increase in plasma norepinepherine levels was associated with late stage exposure. Uterine norepinepherine levels were not affected when measured on days 1 and 6 of gestation but were significantly elevated when measured on days 15.